I would recommend stripping it and cleaning the parts. It is not a hard rifle to work on, being much like the U.S. Krag.

Don't use any harsh abrasive, only cloth, copper wool, and a good cleaner. (I like G-96 Gun Treatment for that.)

Remove the barrel shroud and clean underneath, then use RIG or some other good grease to preserve the barrel for another 100+ years. That was the first mass production Krag, and it is interesting to compare it with the U.S. and Norwegian Krags (which if you don't have, you now have to get or the Krag bug won't let you rest).